Field of the Invention
The invention relates to a simulation apparatus for simulating a peripheral circuit arrangement that can be connected to a regulating device and to a method for simulating a peripheral circuit arrangement that can be connected to a regulating device.
Description of the Background Art
Simulation apparatuses and a selection of hardware components for the simulation apparatuses are known from the printed product catalog “Catalog 2014 Embedded Success dSPACE” on pages 282 to 311 and pages 472 to 491.
Professionals in the field of regulating device development are familiar with the use of a simulation apparatus for simulating a peripheral circuit arrangement that are connected to regulating device(s). Moreover, the use of simulated electrical loads for testing control devices or regulating devices is known. For example, various practical examples of HIL simulators are listed in an SAE scientific paper by A. Wagener et al. from the year 2007 with the title “Hardware-in-the-Loop Test Systems for Electric Motors in Advanced Powertrain Applications.” The circuit complexity in the HIL simulators and/or the conversion effort when changing the regulating device under test (abbreviated as DUT) is/are high.
Alternatively, regulating devices can also be called control devices.
The purpose of a simulation apparatus of the aforementioned type in particular is to test the regulating device for its functionality, without the regulating device having to be brought into its “real” working environment. A realistic simulation of the “real” working environment of the regulating device is a prerequisite for being able to detect at an early stage problems and errors, arising, for example, during the development or modification of the regulating device, in the testing of the regulating device. The intent of the tests, carried out with the simulation apparatus is, for example, to check the power electronic interfaces of the regulating devices. The regulating devices are often called DUT (device under test) in the technical context described above. A frequent goal is to check whether the regulating device or the DUT reacts in the desired manner, whether therefore the regulating device reacts to specific state variables, received via its interfaces, with a suitable output of output variables that are output via its interfaces. The communication of the regulating device with its technical environment occurs via input and output, abbreviated as I/O, in other words, by means of signals that are exchanged via the I/O interfaces between the regulating device and its technical environment.
A simulation apparatus is often used by development engineers to reproduce completely or partially the relevant technical environment of a regulating device of this kind, for example, because the “real” technical environment planned for a later time is not or not yet available to the development engineers. The simulation apparatus comprises at least one simulation computer, also called a computation unit, and at least one I/O interface.
In the case of a motor controller, for example, the motor to be controlled can be simulated totally or partially with the aid of a computation unit or a number of computation units with I/O interfaces. A mathematical copy of the motor is created first for this purpose, therefore a mathematical model and an executable model code that comprises the mathematical model and places the characteristic data and state variables of the motor in a calculable context. The mathematical model and the executable model code derived therefrom are often used as synonyms. The variables, i.e., control signals, acting on the simulated motor, from the regulating device are received by the computation unit via an I/O interface, and state variables of the copied, therefore simulated, motor are calculated on the computation unit, among others, based on the I/O signals and/or the further transmitted and/or stored information using the mathematical model. Specific state variables are typically provided to the motor controller via one or more I/O interface(s). The transmission of the state variables from the simulation apparatus to the motor controller can occur at fixed or variable time intervals or only on demand depending on the nature and purpose of the state variable.
The use of the simulation apparatus very generally results in the considerable advantage that a large spectrum of test cases can be tested and modified environments of the regulating device, e.g., different drive units, can be simulated with only little effort.
It is immediately clear that a simulation apparatus, which is set up for the cited application examples, not only receives signals in the small-signal range from a regulating device, for example, from the motor control device, but electrical large signals as well, if the regulating device has power electronic outputs, as is the case in particular during the control of electric drives. In practice, known circuits for simulating an electrical load are often operated such that the voltage at the output of the regulating device, therefore, for example, the voltage at the output of the power section of a motor controller, is measured metrologically; a corresponding motor current, which would have to flow over the controller terminal, is calculated using a mathematical model of the motor to be simulated with consideration of the motor operating data; and this setpoint current value is transmitted to the current control unit, which then adjusts the determined setpoint current as close to real time as possible by suitably controlling the circuit at the regulating device terminal.
For example, WO 2007/042228 A1, which corresponds to U.S. Pat. No. 8,768,675, which is incorporated herein by reference, describes a circuit that uses a coil as the electrical energy storage device, whose inductance is substantially lower than the inductance of the winding of an electric motor to be simulated. Controlling an electric motor typically requires a plurality of terminals because such drives with relatively high power levels are to be controlled in a multiphase, usually three-phase operation. A pulse-width modulated (PWM) voltage signal, via whose pulse duty factor, the voltage present on average over time at the terminal can be adjusted, is typically present at the controller terminal. The coil is connected by its other terminal via a half-bridge to two auxiliary voltage sources, so that, by switching the one semiconductor switch of the half-bridge, this second terminal of the coil can be connected to a high potential, and, by switching the other semiconductor switch of the bridge, the second terminal of the coil can be connected to a very low potential. It is thus possible to influence the current flow within the coil and to adjust or control the actual value of the current at the terminal of the regulating device to the value of a predefined setpoint current.
If a “semiconductor switch” is discussed in this document, then it is understood to be a switch produced by semiconductor technology, for example, a field-effect transistor, in particular, e.g., a so-called power field-effect transistor, for example, a power MOSFET (metal-oxide-semiconductor field-effect transistor), a bipolar transistor, or a so-called IGBT (insulated-gate bipolar transistor). Use of a semiconductor switch for interrupting, transmitting, and controlling a current is known.
Drive systems, for example, three-phase current motors in passenger vehicles or commercial vehicles, which have an electric or hybrid drive, often move in a power range of over 10 kW to over 100 kW. Particularly in the case of very dynamic load variations, it is necessary here to handle voltages at the regulating device terminal that are in the range of, for example, over 40 V to, for example, over 1000 V, and currents that may be in the range of a few 10 A and at peak several 100 A as well. Apart from assuring the mentioned power or voltage or current ranges at the simulation apparatus interfaces to the regulating device, a relatively low power loss in comparison with existing simulation apparatuses could be desirable, because the heat arising in known simulation apparatuses due to power loss in many application cases requires the installation of cooling units for removing the heat (loss).
Furthermore, a problem of known simulation units is their high cost, because in a line voltage connection a return feed of currents occurs out of the simulation apparatus connected to the line voltage connection, because this type of return feed is subject to strict requirements of the power supply companies. Fulfilling these requirements, in particular in relation to frequency, phase position, and voltage amplitudes of the return feed current, requires costly technical devices, the acquisition of which is normally associated with high investments.